Friday, 20 May 2016

Pick up any introductory psychology textbook and under the "developmental" chapter you're bound to find a description of "groundbreaking" research into newborn babies' imitation skills. The work, conducted in the 1970s, will typically be shown alongside black and white images of a man sticking his tongue out at a baby, and the tiny baby duly sticking out her tongue in response.

The research was revolutionary because it appeared to show that humans are born with the power to imitate – a skill crucial to learning and relationships – and it contradicted the claims of Jean Piaget, the grandfather of developmental psychology, that imitation does not emerge until babies are around nine months old.

Today it may be time to rewrite these textbooks. A new study in Current Biology, more methodologically rigorous than any previous investigation of its kind, has found no evidence to support the idea that newborn babies can imitate.

Janine Oostenbroek and her colleagues tested 106 infants four times: at one week of age, then at three weeks, six weeks, and nine weeks. Data from 64 of the infants was available at all four time points. At each test, the researcher performed a range of facial movements, actions or sounds for 60 seconds each. There were 11 of these displays in total, including tongue protrusions, mouth opening, happy face, sad face, index finger pointing and mmm and eee sounds. Each baby's behaviour during these 60-second periods was filmed and later coded according to which faces, actions or sounds, if any, he or she performed during the different researcher displays.

Whereas many previous studies have compared babies' responses to only two or a few different adult displays, this study was much more robust because the researchers checked to see if, for example, the babies were more likely to stick out their tongues when that's what the researcher was doing, as compared with when the researcher was doing any of the 10 other displays or sounds. Unlike most prior research, this new study also looked to see how any signs of imitation changed over time, at the different testing sessions. According to the researchers, this makes theirs "the most comprehensive, longitudinal study of neonatal imitation to date".

Following these more robust standards, Oostenbroek and her team found no evidence that newborn babies can reliably imitate faces, actions or sounds. For example, let's take the example of tongue protrusions. Averaged across the different testing time points, the babies were no more likely to stick out their tongue when the researcher did so, as compared with the researcher opened her mouth, pulled a happy face or pulled a sad face. In fact, across all the different displays, actions and sounds, there was no situation in which the babies consistently performed a given facial display, gesture or sound more when the researcher specifically did that same thing, than when the researcher was doing anything else.

Based on their results, the researchers said that the idea of "innate imitation modules" and other such concepts founded on the ideal of neonatal imitation "should be modified or abandoned altogether". They said the truth may be closer to what Piaget originally proposed and that imitation probably emerges from around 6 months.